1. Field of the Invention
This invention relates to a frame used in a vehicle, such as a motorcycle, and particularly to the structure of a welded joint for joining two frame members.
2. Description of Related Art
A frame for a motorcycle supports main components such as an engine, a front fork and a rear arm, and has the function of receiving impulsive loads or fatigue failure loads transmitted from the front fork and the rear arm during running.
Since this kind of frame requires high strength and rigidity as well as light weight, a conventional frame includes a plurality of rectangular tube-like frame members which are welded to each other and assembled. In the frame of this type, joint end portions of the plurality of frames are cut obliquely to secure the welding length between the joint end portions, so as to ensure the strength of the welded joint portions.
In the frame disclosed above, the joint end portion of the frame member is cut obliquely when the frame is viewed from the side. Therefore, when the left and right side edges of the joint end portion are inclined to the axis of the frame member, the overall length of the side edges becomes larger compared with when these side edges cross the axis of the frame member at right angles.
However, with the conventional frame, there is nothing mentioned regarding the shapes of the front and rear ends of the frame member. Therefore, the welding length of the welded joint portion is earned only by the left and right side edge portions and thus the welding length of the welded joint portion is hardly sufficient.
An advantage of the present invention is to provide a frame for a vehicle capable of securing a sufficient welding length between joint end portions without complicating the shapes of the joint end portions of the first and second frame members.